External identification plate for instrument transformer



Dec. 1, 1970 R, s, CANNEY 3,543,423

EXTERNAL IDENTIFICATION PLATE FOR INSTRUMENT TRANSFORMER Filed April 2, 1969 2 Sheets-Sheet l Dec. l, 1973 a, :5 CANNEY 3,543,423

EXTERNAL IDENTIFICATION PLATE FOR INSTRUMENT TRANSFORMER Filed April 2, 1969 2 Sheets-Sheet 2 United States Patent 3,543,423 EXTERNAL IDENTIFICATION PLATE FOR INSTRUMENT TRANSFORMER Robert S. Canney, Berwick, Maine, assignor to General Electric Company, a corporation of New York Filed Apr. 2, 1969, Ser. No. 812,669 Int. Cl. G09f 3/02 US. Cl. 40-2.2 5 Claims ABSTRACT OF THE DISCLOSURE An external identification plate for instrument transformers which will show the value for which the trans-. former is connected. The plate is printed on both sides with values according to the full or tapped condition of the secondary winding of the transformer. A terminal post is provided which is connected to the unused terminal of the secondary of the transformer. The external identification plate has either an opening or a pair of transparent detents which cooperate with the post so that the plate can only be put on in a position to show the correct value of the secondary connection. The end of the post is coated with a fluorescent material so that it can be readily seen that the post is in place thus insuring that the correct value of the connection of the secondary terminals is showing.

BACKGROUND OF THE INVENTION This invention relates to instrument transformers and more particularly to an external identification plate for instrument transformers,

As is well known to those skilled in the instrument transformer art, the secondary of many types of instrument transformers may be connected such that either the full secondary winding is utilized or only a portion of the secondary winding is utilized. When the full wind ing is used, the instrument transformer has one rating or ratio while a second rating or ratio is provided when only a portion of the secondary winding is used. For example, in a current transformer, the full winding connection may be 400 amps while the partial or tapped winding connection may be 200 amps. In the same manner in a potential transformer the full secondary winding may be, for example, 60 volts while the partial or tapped secondary winding connection would be for example 120 volts.

As is understood, normally instrument transformers are provided with an external identification plate which provides the correct rating or ratio of the instrument transformer. Where a tapped winding is provided, the identification plate usually has two ratings or ratios marked on such plate, normally one on each side of the plate. It is desirable to be sure that whenever the secondary terminal connections are changed that the identification plate is also changed to show the correct value of the rating or ratio for the changed secondary terminal connections.

Therefore, it is one object of this invention to provide a dual identification plate for an instrument transformer which can only be put on to show the correct rating or ratio for the connections of the secondary terminals.

A further object of this invention is to provide a dual identification plate in combination with a terminal post which cooperate to insure that the correct rating or ratio is shown.

A further object of this invention is to provide a terminal post having an indicator to provide a positive indication that the terminal post is in position thus assuring that the correct rating or ratio is shown on the identification plate.

Patented Dec. 1, 1970 SUMMARY OF THE INVENTION In carrying out this invention in form a ratio identification plate is provided having separate identification numerals on opposite sides of the plate. A terminal post is provided for connection to the unused terminal of the secondary of an instrument transformer. Means are provided in the identification plate cooperating with the terminal post such that the identification plate can only be put on to show the correct ratio for the secondary terminal connection, The end of the terminal post may be coated with a fluorescent material so that it may be readily seen from a distance to assure that the terminal post is in proper position.

The invention which is desired to be protected will be particularly pointed out and distinctly claimed in the claims appended hereto. However, it is believed that this invention and the manner in which its various objects and advantages are obtained as well as other objects and advantages thereof will be more fully understood by reference to the following detailed description of a preferred embodiment of the invention particularly when taken in the light of the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS with the conduit plate removed to show the connections,

of the secondary leads thereto;

FIG. 5 is a front plan view showing another form of ratio identification plate and conduit box cover according to another form of the invention;

FIG. 6 is a front plan view similar to FIG. 5 showing the opposite side of the ratio identification plate;

FIG. 7 is a partial side view partially in section taken on the line 7-7 of FIG. 1 and showing the plate and post of the first form of the invention; and

FIG. 8 is a partial side view partially in section taken on the line 88 of FIG. 5 and showing the plate and post of the second form of the invention.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENT The drawings show the present preferred embodiments of this invention applied to the secondary terminal and conduit box of an instrument transformer. FIGS. 1 through 4 and 7 show the invention in the form wherein an opening is provided in the ratio identification plate while FIGS. 5, 6 and 8 show the invention in a form wherein a pair of detents or depressions are provided in the ratio identification plate. Reference will now be made to the drawings wherein like numerals will be used to indicate like parts throughout the various Views thereof.

Referring first to FIGS. 1 through 4 and 7, an instrument transformer 10 is partially shown having the secondary conduit box 12 with a ratio identification plate 13 and conduit box cover 14. As will be understood, the instrument transformer 10 is provided with a primary winding (not shown) and a tapped secondary winding (not shown) having three terminal connections such as 16, 18 and 20 as shown in FIG. 4. As is understood, the terminal connections 16, 18 and 20 are connected to the secondary winding with the terminals 16 and 20 providing for the full use of the secondary winding while 3 terminals 18 and 20 provide for the use of only half the secondary winding. A ground connection 22 is provided for the secondary lead 24 as is also shown in FIG. 4. Openings 26 and 28 are provided on opposite sides of the conduit box 12 for entrance of the secondary leads 24, as is well understood by those skilled in the art.

When only half of the secondary winding is used, one ratio or rating of the transformer is provided such as for example 1500 amps as shown by the ratio identification plate 13 in FIG. 1. When the full winding is used, another ratio or rating is provided such as, for example, the 3000 amps as shown by the ratio identification plate 13 in FIG. 3. In order to insure that the proper ratio or rating is shown on the ratio identification plate 13, an opening 30 is provided in the ratio identification plate 13. A terminal post 32 is also provided having an end 34 which projects through the opening 30 as shown in FIGS. 1, 2, 3 and 7 whenever the ratio identification plate 13 and the conduit cover 14 is placed over the conduit box in a correct fashion. If desired, the opening 30 may be provided with a grommet such as the grommet 36 which is shown in FIG. 7. The post 32 is mounted in the unused terminal such as, for example, the terminal 16 as is shown in FIG. 4. As will be understood, the post 32 screws into the terminal 16 in the same manner as the screws 38 and 40 which are used to connect the secondary lead 24 to terminals 18 and 20 as is shown in FIG. 4.

When the terminal post 32 is placed in terminal 16 only half the secondary winding is used. With terminal post 32 in position in terminal 16, the conduit cover 13 and ratio identification plate 14 can only be put on to let the lower ratio or rating show, such as for example, the 1500 amps shown in FIG. 1. As will be understood, this is because the opening 30 will fit over end 34 of post 32 in this position but with the 3000 amp position the ratio identification plate 13 would rest on post 32 thereby not fitting properly on conduit cover 14. When post 32 is placed in terminal 18 as is indicated in FIG. 3 when the higher rating or ratio such as the 3000 amps would fit properly with end 34 extending through the opening 30 as shown. Of course, in the same manner it would be impossible to place the ratio identification plate 13 on in a reverse position since the end 34 of post 32 would hold the ratio identification plate 13 oh. the conduit box cover 14 thus not allowing it to be placed on in an incorrect position.

In the form of invention shown in FIGS. 1, 2, 3, 4, and 7, a gasket 11 is provided between the ratio plate 13 and the conduit box cover 14. As is shown, the cover 14 is provided with a slot 15 while the gasket 11 is provided with a pair of holes 17 and 19 to enable post 32 with end 34 to extend through the opening 30 in ratio plate 13. As is well known, ratio plate 13 is fixed to cover 14 by a plurality of screws 21.

In the form of the invention shown in FIGS. 5, 6, and 8, a different type of ratio plate and terminal post is provided. As is shown in these figures, the ratio identification plate 42 is provided with a pair of depressions or indentations 44 and 46 while a terminal post 48 is provided for use with the secondary terminals. As shown in FIG. when the post 48 is in the end terminal, indentation 44 cooperates with the end 50 to allow ratio identification plate 42 to be placed over conduit box cover 52 to show the lower ratio such as 200 amps. When the terminal post 48 is mounted in the central terminal such as is shown in FIG. 6, then indentation 46 cooperates with end 50 of the terminal post 48 to show the higher ratio such as 400 amps. As can be seen especially from FIG. 8, the indentations 44 and 46 are indented in opposite directions. As will be apparent, if the ratio plate 42 is put on in the incorrect position, the plate 42 will rest against post 48 preventing the plate from being secured to the conduit box cover 52. In this form of the invention, plate 42 is made of a plastic material and the indentations 44 and 46 are transparent so that the end 50 may be seen through the plate 42. The end 50 is preferably coated with a fluorescent material so that it can be readily seen from a distance and will readily indicate that the post 48 is in place in the unused terminal. Obviously, if the post 48 is in place in the unused terminal, then the ratio identification plate 42 must be in the correct position and showing the correct value. Of course, if desired, the end 34 of post 32 could also be coated with a fluorescent material to more clearly show that it is in place in the unused terminal.

From the above description it will be readily apparent 'that this invention provides a means for insuring that the proper ratio identification is shown externally according to the connection of the secondary terminals of an instrument transformer.

While there has been shown and described the present preferred embodiments of the invention, it will be obvious to those skilled in the art that various changes may be made without departing from the spirit and scope of the invention.

What is claimed as new and which it is desired to be secured by Letters Patent of the United States is:

1. A ratio identification means for an instrument transformer comprising in combination: an instrument transformer having secondary terminals in a conduit box; a dual ratio identification plate, and a cover for said conduit box; a terminal post secured in the unused terminal of said secondary terminal, means in said dual ratio identification plate cooperating with said post to allow said ratio identification plate to be placed on said conduit box cover in only one position to show the correct ratio connection of said secondary terminals.

2. A ratio identification means for instrument transformers as claimed in claim 1 in which said means is a hole allowing the end of the terminal post to extend through said ratio identification plate.

3. A ratio identification means for instrument transformers as set forth in claim 2 in which the end of said terminal post is coated with a fluorescent material.

4. A ratio identification means for instrument transformers as claimed in claim 1 in which said means are indentation in said ratio identification plate, said indentation cooperating with the end of said terminal post.

5. A ratio identification means for instrument transformers as set forth in claim 4 in which said indentations are transparent and in which the end of said terminal post is coated with a fluorescent material.

References Cited UNITED STATES PATENTS 1,506,576 8/1924 Garrigus 40-2 1,593,193 7/1926 Ryno 402 2,100,041 11/1937 Thieler 402.2

EUGENE R. CAPOZIO, Primary Examiner W. J. CONTRERAS, Assistant Examiner US. Cl. X.R. 40-5; 336137 

